The present invention relates generally to wireless telecommunications and more particularly to a system and method of generating Dual Tone Multi-Frequency tones in the media gateway of a Universal Mobile Telecommunications System network.
A major effort has been made in the last decade to integrate multimedia capabilities and mobile communications. For example, the International Telecommunications Union (ITU) and other organizations have been developing standards and recommendations to insure that mobile communications in the future will be able to support multi-media applications of at least the same quality as existing fixed networks. More specifically, many global research projects have been sponsored in order to develop such next third generation (3G) mobile systems. 3G systems are intended to provide a global mobility with wide range of services including telephony, paging, messaging, Internet and broadband data. In particular, the 3rd Generation Partnership Project (3GPP) was formed for technical development relating to this new mobile communications technology. The Universal Mobile Telecommunications System (UMTS) is a new radio access network, which is optimized for support of 3G services, including multi media-capable mobile communications.
One important aspect of any telecommunications system, including a UMTS network, is support of Dual Tone Multi-Frequency (DTMF) signaling. In fact, the UMTS standards specify that such systems must support DTMF signaling in the mobile-to-land direction. Generally, DTMF is the signal to the phone company that is generated when the telephone network user presses a key on the user equipment (e.g., a mobile phone). In the United States, it is more commonly known as “Touchtone” dialing. DTMF tones are used to allow a telephone network user to do such things as interact with voice mail systems, perform electronic banking, or direct the functioning of an Advanced Intelligence Network service.
Under the UMTS standards, which are described in detail in a number of technical specifications put out by 3GPP, the UMTS network must ensure that the minimum length of tone and the minimum gap between two subsequent tones is achieved. These two times have been defined in the standards. There is no defined maximum length to the tone, however. Significantly, the UMTS standards do not specify how to implement these important concepts.
Thus, there is a need in the art to provide an implementation of the UMTS standards for interconnecting DTMF signals that are present in the UMTS network and playing the tones for different durations.